Film Binoculars to preview focal lengths

I am working as an AD on indie short and our director has been looking for a zoom telescope/binocular type device to be able to preview how different focal lengths will look in a scene before we place the camera and attach a prime lens. Would speed up our workflow as the director would be able to go around the set with this telescope and figure out a rough of the focal lengths he wants to use before the key grip arrives on set to place camera.

The image link below shows the type of telescope device I am thinking of, but I am unable to find out what it is called, so I am not able to buy one for the production.

That's just a directors finder... albeit a really good one. I have a catelog that some of those are in at the studio... I will look them up tomorrow, there's about three different brands of ones like those.

You may be able to get by with just a plain cheap directors finder is you don't need to be able to see the depth of field for each lens, just the focal length. Those kinds of directors finders are just a few hundred bucks. Those like the one in the picture have a groundglass inside and a lens mount on front so you put your actual primes on it and can judge the depth of field as well as the field of view. If you don't need that feature, those kind may be overkill (especially considering they are several several thousand dollars).

The "Fries-Mitchell" finder is the one that is considered the "industry standard"... for some reason I couldn't remember the name. I think that's the one that Steven Spielberg is using in that photo (and his has a big 40mm anamorphic lens on it).

Those all seem to average about $3000-$5000 these days. The Fries is actually less expensive than I remembered it being.

Again, if you don't need to be able to judge depth of field, if you only need to see the angle of view and framing for various focal lengths, you can get by with a much cheaper directors finder that aren't very expensive at all. This little one is the one that I use...

Here's a different view from an cranky old cinematographer: the cinematographer should be the one picking the focal length, not the director. Of course, there are experienced directors who like to make the choice (Ridley Scott among others) and if you are working with one who wants to make the choice, your own choice is either to pass on the job or go along. Going along with Ridley Scott would probably be a great choice to make....

I have never liked any external viewfinder. My own viewfinder is my brain. Over the years I have trained myself to know the fields of view and characteristics of various focal lengths and when shooting with primes can call for the right lens almost every time. (I was wrong once on a 6-day, 35mm shoot.) It's great fun to do, even if no one (except possibly your AC) realizes what you are doing.

Nothing beats looking through the taking lens on the camera to learn their characteristics.

I have to admit, that although I'd like to have a Fries finder... like Rick, I rarely use the one that I have. Like him, I usually just use my eyeballs. Even though I'm holding up my director's finder in my COW icon picture above.

And while it looks cliched, sometimes I'll do the old Hollywood trick of just holding up my hands to frame a shot. It looks corny, but does work.

Also... not to be mean (and because people always have to learn about things the first time somewhere), but if your film's director doesn't know what a director's finder is or is called... I wouldn't be surprised if you don't find a few more things that'd you'd expect any director to know, but doesn't.